Preparation of high silica zeolites bound by zeolite and use thereof

ABSTRACT

This invention relates to a process for producing zeolite-bound high silica zeolites and the use of the zeolite-bound high silica zeolite produced by the process for hydrocarbon conversion. The process is carried out by forming an extrudable paste comprising a mixture of high silica zeolite in the hydrogen form, water, silica, and optionally an extrusion aid, extruding the extrudable paste to form silica-bound high silica zeolite extrudates, and then converting the silica of the binder to a zeolite binder. The zeolite-bound high silica zeolite produced by the process comprises high silica zeolite crystals that are bound together by zeolite binder crystals. The zeolite-bound high silica zeolite finds particular application in hydrocarbon conversion processes, e.g., catalytic cracking, alkylation, disproportionation of toluene, isomerization, and transalkylation reactions.

This application is a divisional of U.S. application Ser. No.09/992,783, filed Nov. 14, 2001, now U.S. Pat. No. 6,517,807 which is acontinuation of U.S. application Ser. No. 09/396,842, filed Sep. 15,1999, now abandoned, which claims priority to U.S. ProvisionalApplication No. 60/101,397, filed Sep. 22, 1998.

FIELD OF THE INVENTION

The present invention relates to a process for preparing high silicazeolites that are bound by zeolite and the use of the zeolite-bound highsilica zeolites as prepared by the process as a catalyst in hydrocarbonconversion.

BACKGROUND OF THE INVENTION

Crystalline microporous molecular sieves, both natural and synthetic,have been demonstrated to have catalytic properties for various types ofhydrocarbon conversion processes. In addition, the crystallinemicroporous molecular sieves have been used as adsorbents and catalystcarriers for various types of hydrocarbon conversion processes, andother applications. These molecular sieves are ordered, porous,crystalline material having a definite crystalline structure asdetermined by x-ray diffraction, within which there are a large numberof smaller cavities which may be interconnected by a number of stillsmaller channels or pores. The dimensions of these channels or pores aresuch as to allow for adsorption of molecules with certain dimensionswhile rejecting those of large dimensions. The interstitial spaces orchannels formed by the crystalline network enable molecular sieves suchas crystalline silicates, crystalline aluminosilicates crystallinesilicoalumino phosphates, and crystalline aluminophosphates, to be usedas molecular sieves in separation processes and catalysts and catalystsupports in a wide variety of hydrocarbon conversion processes.

Zeolites are comprised of a lattice of silica and optionally aluminacombined with exchangeable cations such as alkali or alkaline earthmetal ions. Although the term “zeolites” includes materials containingsilica and optionally alumina, it is recognized that the silica andalumina portions may be replaced in whole or in part with other oxides.For example, germanium oxide, tin oxide, phosphorous oxide, and mixturesthereof can replace the silica portion. Boron oxide, iron oxide, galliumoxide, indium oxide, and mixtures thereof can replace the aluminaportion. Accordingly, the terms “zeolite”, “zeolites” and “zeolitematerial”, as used herein, shall mean not only materials containingsilicon and, optionally, aluminum atoms in the crystalline latticestructure thereof, but also materials which contain suitable replacementatoms for such aluminum, such as gallosilicates. The term“aluminosilicate zeolite”, as used herein, shall mean zeolite materialsconsisting essentially of silicon and aluminum atoms in the crystallinelattice structure thereof.

High silica zeolites, i.e., zeolites with a high molar silica content,are desirable because of their particular catalytic selectivity andtheir thermal stability. Thermal stability is particularly important ifthe zeolite when used as a catalyst or in adsorption procedures isexposed to high temperatures. High silica zeolites are intrinsicallyhydrophobic and remain stable at temperatures in excess of 500° C.

The silica to trivalent metal oxide, e.g., alumina, gallia, and thelike, mole ratio of a given zeolite is often variable. For example,zeolite X can be synthesized with a silica to alumina mole ratio of from2 to 3; zeolite Y can be synthesized with a silica to alumina mole ratiofrom 3 to about 7, and zeolite L can be synthesized with a silica toalumina mole ratio from 4 to about 7. In some zeolites, the upper limitof the silica to trivalent metal oxide mole ratio is virtuallyunlimited. These zeolites are known in the art and include for example,frame work structure types such as MFI, e.g., ZSM-5, MEL, e.g., ZSM-11,MTW, e.g., ZSM-12, and TON, e.g., ZSM-22.

Synthetic zeolites are normally prepared by crystallization of zeolitesfrom a supersaturated synthesis mixture. The resulting crystallineproduct is then dried and calcined to produce a zeolite powder. Althoughthe zeolite powder has good adsorptive properties, its practicalapplications are severely limited because it is difficult to operatefixed beds with zeolite powder. Therefore, prior to using the powder incommercial processes, the zeolite crystals are usually bound.

The zeolite powder is typically bound by forming a zeolite aggregatesuch as a pill, sphere, or extrudate. The extrudate is usually formed byextruding the zeolite in the presence of a non-zeolitic binder anddrying and calcining the resulting extrudate. The binder materials usedare resistant to the temperatures and other conditions, e.g., mechanicalattrition, which occur in various hydrocarbon conversion processes.Examples of binder materials include amorphous materials such asalumina, silica, titania, and various types of clays. It is generallynecessary that the zeolite be resistant to mechanical attrition, thatis, the formation of fines, which are small particles, e.g., particleshaving a size of less than 20 microns.

Although such bound zeolite aggregates have much better mechanicalstrength than the zeolite powder, when such a bound zeolite is used forhydrocarbon conversion, the performance of the zeolite catalyst, e.g.,activity, selectivity, activity maintenance, or combinations thereof,can be reduced because of the binder. For instance, since the binder istypically present in an amount of up to about 50 wt. % of zeolite, thebinder dilutes the adsorption properties of the zeolite aggregate. Inaddition, since the bound zeolite is prepared by extruding or otherwiseforming the zeolite with the binder and subsequently drying andcalcining the extrudate, the amorphous binder can penetrate the pores ofthe zeolite or otherwise block access to the pores of the zeolite, orslow the rate of mass transfer to the pores of the zeolite which canreduce the effectiveness of the zeolite when used in hydrocarbonconversion. Furthermore, when the bound zeolite is used in hydrocarbonconversion, the binder may affect the chemical reactions that are takingplace within the zeolite and also may itself catalyze undesirablereactions, which can result in the formation of undesirable products.

One procedure for making zeolite-bound zeolite involves converting thesilica present in the silica binder of a silica-bound zeolite aggregateto a zeolite binder. The silica-bound zeolite aggregates can be made byextruding a paste containing silica and zeolite. This method comprisesmixing a mixture of silica and zeolite with water and optionally anextrusion aid followed by mulling and extruding the paste to form asilica-bound zeolite extrudate, and subsequently drying and calciningthe extrudate. When such an extrusion procedure is used to preparesilica-bound high silica zeolite extrudates, the extrusion paste usuallydoes not have sufficient plasticity for extrusion of the paste inconventional extruding equipment. Thus, to prepare silica-bound zeoliteaggregates suitable for conversion to zeolite bound high silica zeolite,other techniques must be used such as by mixing the silica and zeoliteand squeezing the mixture together to form a shaped structure havingminimal physical integrity. Such techniques are commercially inefficientand even if used, can result in silica-bound aggregates with less thandesirable physical strength and/or physical integrity.

The present invention provides a process for preparing zeolite-boundhigh silica zeolites useful for hydrocarbon conversion that overcomes orat least mitigates the above-described problems.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a processfor preparing high silica zeolites useful for hydrocarbon conversionthat are bound by zeolite. The process of the present invention iscarried out by forming by extrusion of a silica-bound aggregatecontaining high silica zeolite in the hydrogen form and then convertingthe silica to a zeolite binder such as by aging the silica-boundextrudate in an aqueous ionic solution containing a source of hydroxylions in an amount sufficient to convert the silica to the zeolitebinder.

In another embodiment, the present invention provides a hydrocarbonconversion process for converting organic compounds by contacting theorganic compounds under hydrocarbon conversion conditions with the highsilica-containing zeolite bound by zeolite as synthesized by theprocess. Examples of such processes include acid catalyzed reactionssuch as catalytic cracking, alkylation, dealkylation,disproportionation, and transalkylation reactions and other hydrocarbonconversion processes where cracking is not desired which includecatalyzed reactions, such as, dehydrogenation, hydrocracking,isomerization, dewaxing, oligomerization, and reforming.

DETAILED DESCRIPTION OF THE INVENTION

The process of preparing the zeolite-bound high silica zeolitespreferably comprises the following steps:

(a) forming an extrudable mass comprising high silica zeolite crystalsin the hydrogen form, silica, water, optionally zeolite seeds, andoptionally an extrusion aid;

(b) extruding the extrudable mass to form a silica-bound zeoliteaggregate; and

(c) aging the silica-bound zeolite aggregate at an elevated temperaturein an aqueous ionic solution containing sufficient hydroxy ions to causethe silica binder to be converted to the zeolite binder crystals, e.g.,an initial molar ratio of (OH⁻):(SiO₂) up to 1.2.

The zeolite-bound high silica zeolite produced by the process of thepresent invention will comprise high silica zeolite crystals that arebound together by zeolite binder crystals. The zeolite-bound high silicazeolite generally will not contain significant amounts of non-zeoliticbinder.

The expression “high silica zeolite”, as used herein, means acrystalline zeolite structure which has a tetravalent metal oxide, e.g.,silica, to trivalent metal oxide, e.g., alumina and gallia, mole ratiogreater than 80, e.g., mole ratios from about 100 to about 300,including zeolite structures where the tetravalent metal oxide totrivalent metal oxide ratio is up to about 400 or greater.

The expression “hydrogen form”, as used herein, means that at least 70mole percent, and preferably at least 90 mole percent, of theexchangeable alkali ions of the high silica zeolite are replaced byhydrogen ions. The hydrogen forms of these zeolites [high silicaH-zeolites], which are usually produced synthetically in an alkali formand which occur naturally in alkali form, are produced by means ofcontacting the zeolites with a hydrogen ion containing solution or ahydrogen ion yielding material such as an ammonium ion. That is, anammonium ion compound can be exchanged for the alkali in the zeolitematerial and subsequently, when the zeolite material is heated, theammonium ion compound decomposes and converts the zeolites to theirhydrogen form. The various methods for converting zeolite to thehydrogen form are well known. High silica zeolite for use in the presentprocess can be converted to the hydrogen form using any of these knownprocesses.

High silica zeolites used in the process of the present inventioninclude zeolites having a tetravalent metal oxide to trivalent metaloxide mole ratio of greater than 80. Examples of framework structuretypes which can be synthesized with these mole ratios include large porezeolites having a *BEA structure type. Large pore zeolites have a poresize greater than about 7 Å. Examples of other zeolites includeintermediate pore size zeolites. Intermediate pore size zeolites have apore size from about 5 to about 7 Å. Of the high silica zeolites,framework structure types such as MFI, MEL, MEI, MTW, EUO, MTT, and TONstructure type zeolites are particularly noted. These zeolites and theirisotopic framework structures are described in “Atlas of ZeoliteStructure Types”, eds. W. H. Meier, D. H. Olson and Ch. Baerlocher,Elsevier, Fourth Edition, 1996, which is hereby incorporated byreference. Examples of specific intermediate pore size high silicazeolites include, for example, ZSM-5, ZSM-11, ZSM-12, ZSM-18, ZSM-22,ZSM-23, ZSM-35, ZSM-38, ZSM 48, and ZSM-50.

The high silica zeolites will generally be a composition having thefollowing molar relationship:

X₂O_(3;):(n)YO_(2,)

wherein X is a trivalent element, such as titanium, aluminum, iron,boron, and/or gallium and Y is a tetravalent element such as silicon,tin, and/or germanium; and n has a value greater than 80, e.g., 100.

When the high silica zeolite is an intermediate pore size zeolite, thezeolite will generally have a silica to trivalent metal oxide, e.g.alumina, mole ratio from greater than 80:1 to about 700:1 and usuallyfrom about 100:1 to about 500:1.

When the high silica zeolites are an intermediate pore sizegallosilicate zeolite, the zeolite will generally be a compositionhaving the following molar relationship:

Ga₂O₃ :ySiO₂

wherein y will have a value greater than 80 and usually from about 100to about 500. The zeolite framework may contain only gallium and siliconatoms or may also contain a combination of gallium, aluminum, andsilicon.

The term “average particle size” as used herein, means the arithmeticaverage of the diameter distribution of the crystals on a volume basis.

The average particle size of the crystals of the high silica zeolite ispreferably from about 0.1 to about 15 microns (μm). For someapplications, the average particle size will preferably be at leastabout 1 to about 6 microns (μm). For other applications such as thecracking of hydrocarbons, the preferred average particle size issmaller, e.g., from about 0.1 to about 3.0 microns (μm).

When the high silica zeolites is intermediate pore size gallosilicatezeolite, e.g., a MFI structure type gallosilicate zeolite, the binderzeolite will usually be an intermediate pore size zeolite having asilica to gallia mole ratio greater than 100. The zeolite of the bindercrystals can also have higher silica to gallia mole ratios, e.g.,greater than 200, 500, 1000, etc.

The zeolite of the binder can have a structure type that is the same oris different from the structure type of the high silica zeolite. Thestructure type of the second zeolite will depend on the intended use ofthe zeolite-bound high silica zeolite.

When the zeolite of the binder crystals is aluminosilicate zeolite, thesilica to alumina mole ratio of the zeolite will usually depend upon thestructure type of the zeolite and particular hydrocarbon process inwhich the zeolite-bound high silica zeolite is utilized and is thereforenot limited to any particular ratio. In applications where thealuminosilicate zeolite is an intermediate pore size zeolite and lowacidity is desired, the binder zeolite will usually have a silica toalumina mole ratio greater than the silica to alumina mole ratio of thezeolite of the high silica zeolite crystals. The binder zeolite can havehigh silica to alumina mole ratios, e.g., 200:1, 300:1, 500:1, 1,000:1,etc. In certain applications, the zeolite binder may be a Silicalite 1i.e., the binder zeolite is a MFI structure type substantially free ofalumina or Silicalite 2, i.e., the binder zeolite is a MEL structuretype substantially free of alumina.

The zeolite binder crystals will usually have a smaller size than thecrystals of the high silica zeolite and will preferably have an averageparticle size of less than 1 micron (μm), for example, from about 0.1 toabout 0.5 micron (μm). The zeolite binder crystals bind the high silicazeolite crystals and preferably intergrow and form an over-growth whichcoats or partially coats the high silica zeolite. Preferably, thecoating is resistant to attrition.

The zeolite binder is usually present in the zeolite-bound high silicazeolite in an amount in the range of from about 10 to about 60% byweight based on the weight of the zeolite-bound high silica zeolite and,more preferably from about 20 to about 50% by weight.

The high silica zeolite may be prepared in the usual way i.e., a zeolitesynthesis mixture is prepared and aged to allow crystallization. Theresulting product is then washed, dried, calcined, and converted to thehydrogen form. Next, the high silica H-zeolite is mixed with silica,water, and optionally an extrusion aid, formed into an extrudable paste,and extruded to form an extrudate. Typical extruders include extrusionpresses, which are also termed ram extruders, and screw extruders. In anextrusion press or ram extruder, a mass of material is forced through adie by means of a plunger or piston which may be mechanically orhydraulically operated. In a screw extruder, the material is transportedfrom a feed point to the die by means of a turning screw or auger. Afterformation, drying and calcining of the extrudates, the silica binder ofthe extrudate is then converted to the zeolite binder.

To convert the silica binder to the zeolite binder, the zeoliteextrudate is usually aged, i.e. converted, at elevated temperature. Asuitable aging temperature may range from 95° to 200° C. depending onthe type of zeolite. Zeolites such as MFI-type zeolites may be aged attemperatures such as 130° to 170°, preferably 145° to 155° C., mostpreferably around 150°.

The time during which the extrudate may be aged will depend on thezeolite being aged, but may be for example, from 20 to 140 hours.

The zeolite-bound high silica zeolite is preferably prepared by a threestep procedure. The first step involves the preparation of the highsilica H-zeolite crystals. Processes for preparing the high silicazeolite crystals are known to persons skilled in the art. For example,the preparation of high silica ZSM-5 is disclosed in U.S. Pat. No.3,702,886. After preparation of the crystals, the high silica zeolitecan be calcined and then converted to the hydrogen form such as by ionexchange of the alkali form with intermediate ammonium cation followedby calcination to remove ammonia and form high silica H-zeolite.

In the second step, a silica-bound zeolite aggregate is prepared byforming a mixture comprising the high silica H-zeolite crystals, asilica gel or sol, water, optionally seeds, and optionally an extrusionaid, until a homogeneous composition in the form of an extrudable pastedevelops. The silica binder used in preparing the silica-bound zeoliteaggregate is preferably a mixture of a colloidal silica in combinationwith a pyrogenic silica or the like and optionally can contain variousamounts of trivalent elements, e.g., aluminum, gallium, boron, iron,zinc, or mixtures thereof. The amount of silica used is such that thecontent of the zeolite in the dried extrudate at this stage will rangefrom about 40 to 90% by weight more preferably from about 50 to about80% by weight, with the balance being primarily silica, e.g. about 20 to50% by weight silica.

The resulting paste is then extruded in an extruder, and then cut intosmall strands, e.g., approximately 2 mm diameter extrudates. Theextrudates are dried at 100° C. to 150° C. for a period of 4-12 hoursand then are cacined in air at a temperature of from about 400° C. to550° C. for a period of from about 1 to 10 hours.

The final step of the three step process is the conversion of the silicapresent in the silica-bound high silica zeolite to binder crystals ofzeolite which bind the high silica zeolite crystals together. The highsilica zeolite crystals are held together without the use of asignificant amount of non-zeolite binder. Preferably, the zeolite-boundhigh silica zeolite contains less than 10 percent by weight, based onthe weight of the high silica zeolite and binder zeolite, ofnon-zeolitic binder, more preferably, contains less than 5 percent byweight, and, most preferably, the catalysts is substantially free ofnon-zeolitic binder.

To prepare the zeolite-bound high silica zeolite, the silica-boundaggregate which can also contain zeolite seed crystals is preferablyfirst aged in an appropriate aqueous solution at elevated temperature.The use of zeolite colloidal seeds is disclosed in provisional U.S.application serial No. 60/067,417, filed Dec. 3, 1997, now U.S.application Ser. No. 09/204,736, filed Dec. 3, 1998, now U.S. Pat. No.6,150,293 and entitled “Preparation of Zeolite Bound Zeolite”, which ishereby incorporated by reference. Next, the contents of the solution andthe temperature at which the aggregate is aged are selected to convertthe amorphous silica binder into the zeolite binder. The newly-formedzeolite is produced as crystals. The crystals may grow on and/or adhereto the high silica zeolite crystals, and may also be produced in theform of new intergrown crystals, which are generally much smaller thanthe initial crystals, e.g., of sub-micron size. These newly formedcrystals may grow together and interconnect.

The nature of the zeolite formed in the secondary synthesis conversionof the silica to zeolite may vary as a function of the composition ofthe secondary synthesis solution and synthesis aging conditions. Thesecondary synthesis solution is preferably an aqueous ionic solutioncontaining a source of hydroxy ions, optionally an organic structuredirecting agent, and optionally various amounts of trivalent elements,e.g., aluminum, gallium, boron, iron, zinc, or mixtures thereof,sufficient to convert the silica to the desired zeolite. It isimportant, however, that the aging solution have a pH which is not tooalkaline, e.g., an initial molar ratio of OH⁻:SiO₂ of 0.05 to 0.12. Ifthe pH is too high the silica present in the silica-bound zeoliteextrudate may tend to dissolve out of the extrudate.

The zeolite-bound high silica zeolite may be further ion exchanged as isknown in the art either to replace at least in part the metals presentin the zeolite with a different cation, e.g. a metal from Group IB toVIII of the Periodic Table or to provide a more acidic form of thezeolite. Particularly preferred cations are those which render thematerial catalytically active, especially for certain hydrocarbonconversion reactions. These include hydrogen, rare earth metals, and oneor more metals of Groups IIA, IIIA, IVA, VA, VIA, VIIA, VIII, IB, IIB,IIIB, IVB, and VB of the Periodic Table of the Elements. Examples ofsuitable metals include Group VIII metals (i.e., Pt. Pd, Ir, Rh, Os, Ru,Ni, Co and Fe), Group IVA metals (i.e., Sn and Pb), Group VB metals(i.e., Sb and Bi), and Group VIIB metals (i.e., Mn, Tc and Re). Noblemetals (i.e., Pt, Pd, Ir, Rh, Os and Ru) are sometimes preferred.

The zeolite-bound high silica zeolite of the present invention can beused in processing hydrocarbon feedstocks. Hydrocarbon feed-stockscontain carbon compounds and can be from many different sources, such asvirgin petroleum fractions, recycle petroleum fractions, tar sand oil,and, in general, can be any carbon containing fluid susceptible tozeolitic catalytic reactions. Depending on the type of processing thehydrocarbon feed is to undergo, the feed can contain metal or can befree of metals. Also, the feed can also have high or low nitrogen orsulfur impurities.

The conversion of hydrocarbon feeds can take place in any convenientmode, for example, in fluidized bed, moving bed, or fixed bed reactorsdepending on the types of process desired.

The zeolite-bound high silica zeolite by itself or in combination withone or more catalytically active substances can be used as a catalyst orsupport for a variety of organic, e.g., hydrocarbon compound, conversionprocesses. Examples of such conversion processes include, asnon-limiting examples, the following:

(A) The catalytic cracking of a naphtha feed to produce light olefins.Typical reaction conditions include from about 500° C. to about 750° C.,pressures of subatmospheric or atmospheric, generally ranging up toabout 10 atmospheres (gauge) and residence time (volume of the catalyst,feed rate) from about 10 milliseconds to about 10 seconds.

(B) The catalytic cracking of high molecular weight hydrocarbons tolower weight hydrocarbons. Typical reaction conditions for catalyticcracking include temperatures of from about 400° C. to about 700° C.,pressures of from about 0.1 atmosphere (bar) to about 30 atmospheres,and weight hourly space velocities of from about 0.1 to about 100 hr⁻¹.

(C) The transalkylation of aromatic hydrocarbons in the presence ofpolyalkylaromatic hydrocarbons. Typical reaction conditions include atemperature of from about 200° C. to about 500° C., a pressure of fromabout atmospheric to about 200 atmospheres, a weight hourly spacevelocity of from about 1 to about 100 hr⁻¹ and an aromatichydrocarbon/polyalkylaromatic hydrocarbon mole ratio of from about 1/1to about 16/1.

(D) The isomerization of aromatic (e.g., xylene) feedstock components.Typical reaction conditions for such include a temperature of from about230° C. to about 510° C., a pressure of from about 0.5 atmospheres toabout 50 atmospheres, a weight hourly space velocity of from about 0.1to about 200 and a hydrogen/hydrocarbon mole ratio of from about 0 toabout 100.

(E) The dewaxing of hydrocarbons by selectively removing straight chainparaffins. The reaction conditions are dependent in large measure on thefeed used and upon the desired pour point. Typical reaction conditionsinclude a temperature between about 200° C. and 450° C., a pressure upto 3,000 psig and a liquid hourly space velocity from 0.1 to 20.

(F) The alkylation of aromatic hydrocarbons, e.g., benzene andalkylbenzenes, in the presence of an alkylating agent, e.g., olefins,formaldehyde, alkyl halides and alcohols having 1 to about 20 carbonatoms. Typical reaction conditions include a temperature of from about100° C. to about 500° C., a pressure of from about atmospheric to about200 atmospheres, a weight hourly space velocity of from about 1 hr⁻¹ toabout 100 hr⁻¹ and an aromatic hydrocarbon/alkylating agent mole ratioof from about 1/1 to about 20/1.

(G) The alkylation of aromatic hydrocarbons, e.g., benzene, with longchain olefins, e.g., C₁₄ olefin. Typical reaction conditions include atemperature of from about 50° C. to about 200° C., a pressure of fromabout atmospheric to about 200 atmospheres, a weight hourly spacevelocity of from about 2 hr⁻¹ to about 2000 hr⁻¹ and an aromatichydrocarbon/olefin mole ratio of from about 1/1 to about 20/1. Theresulting product from the reaction are long chain alkyl aromatics whichwhen subsequently sulfonated have particular application as syntheticdetergents.

(H) The alkylation of aromatic hydrocarbons with light olefins toprovide short chain alkyl aromatic compounds, e.g., the alkylation ofbenzene with propylene to provide cumene. Typical reaction conditionsinclude a temperature of from about 10° C. to about 200° C., a pressureof from about 1 to about 30 atmospheres, and an aromatic hydrocarbonweight hourly space velocity (WHSV) of from 1 hr⁻¹ to about 50 hr⁻¹.

(I) The hydrocracking of heavy petroleum feedstocks, cyclic stocks, andother hydrocrack charge stocks. The zeolite-bound high silica zeolitewill contain an effective amount of at least one hydrogenation componentof the type employed in hydrocracking catalysts.

(J) The alkylation of a reformate containing substantial quantities ofbenzene and toluene with fuel gas containing short chain olefins (e.g.,ethylene and propylene) to produce mono- and dialkylates. Preferredreaction conditions include temperatures from about 100° C. to about250° C., a pressure of from about 100 to about 800 psig, a WHSV-olefinfrom about 0.4 hr⁻¹ to about 0.8 hr⁻¹, a WHSV-reformate of from about 1hr⁻¹ to about 2 hr⁻¹ and, optionally, a gas recycle from about 1.5 to2.5 vol/vol fuel gas feed.

(K) The alkylation of aromatic hydrocarbons, e.g., benzene, toluene,xylene, and naphthalene, with long chain olefins, e.g., C₁₄ olefin, toproduce alkylated aromatic lube base stocks. Typical reaction conditionsinclude temperatures from about 100° C. to about 400° C. and pressuresfrom about 50 to 450 psig.

(L) The alkylation of phenols with olefins or equivalent alcohols toprovide long chain alkyl phenols. Typical reaction conditions includetemperatures from about 100° C. to about 250° C., pressures from about 1to 300 psig and total WHSV of from about 2 hr⁻¹ to about 10 hr⁻¹.

(M) The conversion of light paraffins to olefins and/or aromatics.Typical reaction conditions include temperatures from about 425° C. toabout 760° C. and pressures from about 10 to about 2000 psig.

(N) The conversion of light olefins to gasoline, distillate and luberange hydrocarbons. Typical reaction conditions include temperatures offrom about 175° C. to about 375° C. and a pressure of from about 100 toabout 2000 psig.

(O) Two-stage hydrocracking for upgrading hydrocarbon streams havinginitial boiling points above about 200° C. to premium distillate andgasoline boiling range products or as feed to further fuels or chemicalsprocessing steps. The first stage can be the zeolite-bound high silicazeolite comprising one or more catalytically active substances, e.g., aGroup VIII metal, and the effluent from the first stage would be reactedin a second stage using a second zeolite, e.g., zeolite Beta, comprisingone or more catalytically active substances, e.g., a Group VIII metal,as the catalyst. Typical reaction conditions include temperatures fromabout 315° C. to about 455° C., a pressure from about 400 to about 2500psig, hydrogen circulation of from about 1000 to about 10,000 SCF/bbland a liquid hourly space velocity (LHSV) of from about 0.1 to 10.

(P) A combination hydrocracking/dewaxing process in the presence of thezeolite-bound high silica zeolite comprising a hydrogenation componentand a zeolite such as zeolite Beta. Typical reaction conditions includetemperatures from about 350° C. to about 400° C., pressures from about1400 to about 1500 psig, LHSVs from about 0.4 to about 0.6 and ahydrogen circulation from about 3000 to about 5000 SCF/bbl.

(Q) The reaction of alcohols with olefins to provide mixed ethers, e.g.,the reaction of methanol with isobutene and/or isopentene to providemethyl-t-butyl ether (MTBE) and/or t-amyl methyl ether (TAME). Typicalconversion conditions include temperatures from about 20° C. to about200° C., pressures from 2 to about 200 atm, WHSV (gram-olefin per hourgram-zeolite) from about 0.1 hr⁻¹ to about 200 hr⁻¹ and an alcohol toolefin molar feed ratio from about 0.1/1 to about 5/1.

(R) The disproportionation of aromatics, e.g. the disproportionationtoluene to make benzene and paraxlene. Typical reaction conditionsinclude a temperature of from about 200° C. to about 760° C., a pressureof from about atmospheric to about 60 atmosphere (bar), and a WHSV offrom about 0.1 hr⁻¹ to about 30 hr⁻¹.

(S) The conversion of naphtha (e.g., C₆-C₁₀) and similar mixtures tohighly aromatic mixtures. Thus, normal and slightly branched chainedhydrocarbons, preferably having a boiling range above about 40° C., andless than about 200° C., can be converted to products having asubstantial higher octane aromatics content by contacting thehydrocarbon feed with the zeolite at a temperature in the range of fromabout 400° C. to 600° C., preferably 480° C. to 550° C. at pressuresranging from atmospheric to 40 bar, and liquid hourly space velocities(LHSV) ranging from 0.1 to 15.

(T) The adsorption of alkyl aromatic compounds for the purpose ofseparating various isomers of the compounds.

(U) The conversion of oxygenates, e.g., alcohols, such as methanol, orethers, such as dimethylether, or mixtures thereof to hydrocarbonsincluding olefins and aromatics with reaction conditions including atemperature of from about 275° C. to about 600° C., a pressure of fromabout 0.5 atmosphere to about 50 atmospheres and a liquid hourly spacevelocity of from about 0.1 to about 100.

(V) The oligomerization of straight and branched chain olefins havingfrom about 2 to about 5 carbon atoms. The oligomers which are theproducts of the process are medium to heavy olefins which are useful forboth fuels, i.e., gasoline or a gasoline blending stock, and chemicals.The oligomerization process is generally carried out by contacting theolefin feedstock in a gaseous state phase with a zeolite-bound highsilica zeolite at a temperature in the range of from about 250° C. toabout 800° C., a LHSV of from about 0.2 to about 50 and a hydrocarbonpartial pressure of from about 0.1 to about 50 atmospheres. Temperaturesbelow about 250° C. may be used to oligomerize the feedstock when thefeedstock is in the liquid phase when contacting the zeolite-bound highsilica zeolite catalyst. Thus, when the olefin feedstock contacts thecatalyst in the liquid phase, temperatures of from about 10° C. to about250° C. may be used.

(W) The conversion of C₂ unsaturated hydrocarbons (ethylene and/oracetylene) to aliphatic C₆₋₁₂ aldehydes and converting said aldehydes tothe corresponding C₆₋₁₂ alcohols, acids, or esters.

In general, the, catalytic conversion conditions over the zeolite-boundhigh silica zeolite catalyst include a temperature of from about 100° C.to about 760° C., a pressure of from about 0.1 atmosphere (bar) to about200 atmospheres (bar), a weight hourly space velocity of from about 0.08hr⁻¹ to about 2,000 hr⁻¹.

Although many hydrocarbon conversion processes prefer that the bindercrystals have lower acidity to reduce undesirable reactions external tothe high silica zeolite crystals, some processes prefer that the bindercrystals have higher acidity, e.g., cracking reactions.

The zeolite-bound high silica zeolite can have particular application inthe vapor phase disproportionation of toluene. Such vapor phasedisproportionation comprises contacting toluene under disproportionationconditions with zeolite-bound high silica zeolite to yield a productmixture which comprises a mixture of unreacted (unconverted) toluene,benzene and xylene. In the more preferred embodiment, the catalyst isfirst selectivated prior to use in the disproportionation process toenhance conversion of toluene to xylene and to maximize the catalystselectivity towards the production of paraxylene. Processes forselectivating the catalyst are known to persons skilled in the art. Forinstance, selectivation may be accomplished by exposing the catalyst ina reactor bed to a thermally decomposable organic compound, e.g.toluene, at a temperature in excess of the decomposition temperature ofsaid compound, e.g. from about 480° C. to about 650° C., more preferably540° C. to about 650° C., at a WHSV in the range of from about 0.1 to 20lbs of feed per pound of catalyst per hour, at a pressure in the rangeof from about 1 to 100 atmospheres, and in the presence of 0 to about 2moles of hydrogen, more preferably from about 0.1 to about 2 moles ofhydrogen per mole of organic compound, and optionally in the presence of0-10 moles of nitrogen or another inert gas per mole of organiccompound. This process is conducted for a period of time until asufficient quantity of coke has been deposited on the catalyst surface,generally at least about 2% by weight and more preferably from about 8to about 40% by weight of coke. In a preferred embodiment, such aselectivation process is conducted in the presence of hydrogen in orderto prevent rampant formation of coke on the catalyst.

Selectivation of the catalyst can also be accomplished by treating thecatalyst with a selectivation agent such as an organosilicon compound.Examples of organosilicon compounds include polysiloxane includingsilicones, a siloxane, and a silane including disilanes andalkoxysilanes.

Silicone compounds that find particular application can be representedby the formula:

wherein R₁ is hydrogen, fluoride, hydroxy, alkyl, aralkyl, alkaryl orfluoro-alkyl. The hydrocarbon substituents generally contain from 1 to10 carbon atoms and preferably are methyl or ethyl groups. R₂ isselected from the same group as R₁, and n is an integer of at least 2and generally in the range of 2 to 1000. The molecular weight of thesilicone compound employed is generally between 80 and 20,000 andpreferably 150 to 10,000. Representative silicone compounds includeddimethylsilicone, diethylsilicone, phenylmethylsilicone, methylhydrogensilicone, ethylhydrogensilicone, phenylhydrogensilicone,methylethylsilicone, phenylethylsilicone, diphenylsilicone, methyltrifluoropropylsilicone, ethyltrifluoropropylsilicone, tetrachlorophenylmethyl silicone, tetrachlorophenylethyl silicone, tetrachlorophenylhydrogen silicone, tetrachlorophenylphenyl silicone,methylvinylsilicone and ethylvinylsilicone. The silicone compound neednot be linear but may be cyclic as for examplehexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, hexaphenylcyclotrisiloxane and octaphenylcyclotetrasiloxane. Mixtures of thesecompounds may also be used as well as silicones with other functionalgroups.

Useful siloxanes or polysiloxanes include as non-limiting exampleshexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethyldisiloxane, octamethytrisiloxane,decamethyltetrasiloxane, hexaethylcyclotrisiloxane, octaethylcyclotetrasiloxane, hexaphenylcyclotrisiloxane and octaphenylcyclotetrasiloxane.

Useful silanes, disilanes, or alkoxysilanes include organic substitutedsilanes having the general formula:

wherein R₃ is a reactive group such as hydrogen, alkoxy, halogen,carboxy, amino, acetamide, trialkylsilyoxy, R₄, R₅ and R₆ can be thesame as R₃ or can be an organic radical which may include alkyl of from1 to 40 carbon atoms, alkyl or aryl carboxylic acid wherein the organicportion of the alkyl contains 1 to 30 carbon atoms and the aryl groupcontains 6 to 24 carbon which may be further substituted, alkylaryl andarylalkyl groups containing 7 to 30 carbon atoms. Preferably, the alkylgroup for an alkyl silane is between 1 and 4 carbon atoms in chainlength.

When used the vapor phase disproportionation of toluene, the catalystcan comprise a first phase of crystals of MFI-type high silica zeolitecrystals having a micron average particle size from about 2 to about 6,a silica to alumina mole ratio of from greater than 80 to about 200:1,preferably, greater than 80:1 to about 120:1, having adheredstructurally to the surfaces thereof particles of zeolite binder, e.g.,MEL or MFI structure type having an average particle size of less thanabout one micron (μm) and having a alumina to silica mole ratio inexcess of about 200:1 to about 10,000:1 including Silicalite 1 orSilicalite 2.

Once the catalyst has been selectivated to the desired degree, reactorselectivation conditions are changed to disproportionation conditions.Disproportionation conditions include a temperature between about 400°C. and about 550° C., more preferably between about 425° C. and about510° C., at a hydrogen to toluene mole ratio of from 0 to about 10,preferably between about 0.1 and 5 and more preferably from about 0.1 to1, at a pressure between about 1 atmosphere and 100 atmospheres andutilizing WHSV of between about 0.5 and 50.

The disproportionation process may be conducted as a batch,semi-continuous or continuous operation using a fixed or moving bedcatalyst system deposited in a reactor bed. The catalyst may beregenerated after coke deactivation by burning off the coke to a desiredextent in an oxygen-containing atmosphere at elevated temperatures asknow in the art.

The zeolite-bound high silica zeolite finds particular application as acatalyst in a process for isomerizing one or more xylene isomers in a C₈aromatic feed to obtain ortho-, meta-, and para-xylene in a ratioapproaching the equilibrium value. In particular, xylene isomerizationis used in conjunction with a separation process to manufactureparaxylene. For example, a portion of the para-xylene in a mixed C₈aromatics stream may be recovered using processes known in the art,e.g., crystallization, adsorption, etc. The resulting stream is thenreacted under xylene isomerization conditions to restore ortho-, meta-,and paraxylenes to a near equilibrium ratio. Ethylbenzene in the feed iseither removed from the stream or is converted during the process toxylenes or to benzene which are easily separated by distillation. Theisomerate is blended with fresh feed and the combined stream isdistilled to remove heavy and light by-products. The resultant C₈aromatics stream is then recycled to repeat the cycle.

It is important that xylene isomerization catalysts produce a nearequilibrium mixture of xylenes and it is also usually desirable that thecatalyst convert ethylbenzene with very little net loss of xylenes. Thesilica to trivalent metal oxide, e.g., alumina and gallia, mole ratiosof the high silica zeolite and zeolite binder can be selected to balancexylene isomerization and ethylbenzene dealkylation while minimizingundesirable side reactions. Accordingly, the zeolite-bound high silicazeolite finds particular application in a hydrocarbon conversion processwhich comprises contacting a C₈ aromatic stream containing one or morexylene isomers or ethylbenzene or a mixture thereof, under isomerizationconditions with the zeolite-bound high silica zeolite. Preferably, atleast 30% of the ethylbenzene is converted.

In the vapor phase, suitable isomerization conditions include atemperature in the range of from about 250° C. to about 600° C.,preferably from about 300° C. to about 550° C., a pressure in the rangeof from about 0.5 to about 50 atm abs, preferably from about 10 to about25 atm abs, and a weight hourly space velocity (WHSV) of from about 0.1to about 100, preferably from about 0.5 to about 50. Optionally,isomerization in the vapor phase is conducted in the presence of fromabout 3.0 to about 30.0 moles of hydrogen per mole of alkylbenzene. Ifhydrogen is used, the metal components of the zeolite-bound high silicazeolite preferably includes from about 0.1 to about 2.0 wt. % of ahydrogenation/dehydrogenation component selected from Group VIII of thePeriodic Table of Elements, especially platinum, palladium, or nickel.By Group VIII metal component, it is meant the metals and theircompounds such as oxides and sulfides.

The zeolite-bound high silica zeolite invention is useful as a catalystin a process for cracking a naphtha feed, e.g., C₄ _(⁺) naphtha feed,particularly a C₄ _(⁻) 290° C. naphtha feed to produce low molecularweight olefins, e.g., C₂ through C₄ olefins, particularly ethylene andpropylene. Such a process is preferably carried out by contacting thenaphtha feed at temperatures ranging from about 500° C. to about 750°C., more preferably about 550° C. to about 675° C., at a pressure fromsubatmospheric up to about 10 atmospheres, but preferably from about 1atmosphere to about 3 atmospheres.

The zeolite-bound high silica zeolite is useful as a catalyst in thetransalkylation of polyalkylaromatic hydrocarbons. Examples of suitablepolyalkylaromatic hydrocarbons include di-, tri-, and tetra-alkylaromatic hydrocarbons, such as diethylbenzene, triethylbenzene,diethylmethylbenzene (dietyl-toluene), diisopropyl-benzene,triisopropylbenzene, diisopropyltoluene, dibutylbenzene, and the like.Preferred polyalkylaromatic hydro-carbons are the dialkyl benzenes.Particularly preferred polyalkyl-aromatic hydrocarbons arediisopropylbenzene and diethylbenzene.

The transalkylation process will preferably have a molar ratio ofaromatic hydrocarbon to polyalkylaromatic hydrocarbon of preferably fromabout 0.5:1 to about 50:1, and more preferably from about 2:1 to about20:1. The reaction temperature will preferably range from about 340° C.to about 500° C. to maintain at least a partial liquid phase, and thepressure will be preferably in the range of about 50 psig to about 1,000psig, preferably from about 300 psig to about 600 psig. The weighthourly space velocity will range from about 0.1 to about 10.

The zeolite-bound high silica zeolite is also useful in processes forconverting aromatic compounds by the dehydrocyclo-oligomerization ofaliphatic hydrocarbons. Example of suitable paraffins includingaliphatic hydrocarbons containing 2 to 12 carbon atoms. The hydrocarbonsmay be straight chain, open or cyclic and may be saturated orunsaturated. Example of hydrocarbons include propane, propylene,n-butane, n-butenes, isobutane, isobutene, and straight- andbranch-chain and cyclic pentanes, pentenes, hexanes, and hexenes.

The dehydrocyclo-oligomerization conditions include a temperature offrom about 200° C. to about 700° C., a pressure of from about 0.1atmosphere to about 60 atmospheres, a weight hourly space velocity(WHSV) of from about 0.1 to about 400 and a hydrogen/hydrocarbon moleratio of from about 0 to about 20.

The zeolite-bound high silica zeolite used in thedehydrocyclo-oligomerization process preferably comprises of anintermediate pore size high silica zeolite such a MFI type zeolite(example ZSM-5), and binder crystals of a intermediate pore size such asa MEL structure type. The catalyst preferably contains gallium. Galliummay be incorporated during the synthesis of the zeolite or it may beexchanged or impregnated or otherwise incorporated into the zeoliteafter synthesis. Preferably 0.05 to 10, and most preferably 0.1 to 2.0wt. % gallium is associated with the zeolite-bound high silica zeolitecatalyst. The gallium can be associated with the high silica zeolite,binder zeolite, or both zeolites.

The following examples illustrate the invention.

EXAMPLE 1 Zeolite-bound MFI Gallosilicate High Silica Zeolite

A. Preparation of MFI Structure Type Gallosilicate High Silica H-zeolite

High silica MFI structure type gallosilicate having a silica to galliamole ratio of 190 was prepared as follows:

Components Use Quantity for Preparation (Grams) Solution A NaOH pellets(98.6%)  18.82 Ga₂O₃ (99.995%)  4.81 Water (conductivity less than 5μS/cm)  50.00 Rinse Water 185.01 Solution B Colloidal Silica (LudoxHS-40) 773.00 Water (conductivity less than 5 μS/cm) 100.03 Solution CTetrapropylammonium bromide 123.72 Water (conductivity less than 5μS/cm) 425.00 Rinse Water 125.00

The ingredients of Solution A were dissolved by boiling until a clearsolution was obtained. Solution A was then cooled to ambient temperatureand water loss from boiling was corrected.

Solution B was prepared by adding the specified amount of the colloidalsilica to a 2 liter glass beaker, adding the specified amounts of waterto the contents of the beaker, and then homogenizing the mixture bystirring. Solution C was prepared by adding the specified amounts ofTPABr and water to a 1 liter glass beaker and mixing. Solution C wasadded to Solution B using the rinse water to quantitatively transferSolution C. The two solutions were mixed for two minutes and then 7.88grams of colloidal MFI seed suspension containing 0.64 mg. solids/gr.were added. Next, Solution A was added together with its rinse water.The contents were mixed for 10 minutes. A just pourable visuallyhomogeneous gel was obtained. The gel had the following compositionexpressed in moles of pure oxide:

0.45Na₂O/0.90TPA Br/0.05Ga₂O₃/10SiO₂/147H₂O

The synthesis mixture contained 2.8 wt. ppm seeds.

An amount of 1789.47 grams of the synthesis mixture was transferred to a2 liter stainless steel autoclave. The autoclave was placed in a roomtemperature oven and heated to 150° C. in 2 hours and maintained at 150°C. at this temperature for 42 hours.

The product was removed from the autoclave, washed with water to a pH of10.3, and dried over night at 120° C. The amount of product recoveredwas 328.4 grams. The product was calcined in air at 490° C. for 24 hourswith a heat-up rate of 1.5° C./min. The weight loss on calcination was11.5 wt. %. The characteristics of the calcined product were thefollowing:

XRD: Excellently Crystalline MFI

SEM: Uniformly spherical 2.3 micron size crystals

Elemental: SiO₂/Ga₂O₃=190

The portion of the calcined product was converted to the hydrogen formby mixing it with 1200 grams of 10% by weight of ammonium nitrate for 16hours at 69.5° C. The product was washed twice with 900 grams of waterand then dried at 120° C. The ammonium exchange, washing and dryingprocedure were then repeated. Next, the ammonium exchanged product wascalcined in air at 490° C. for 20 hours.

B. Preparation of Silica-bound MFI Gallosilicate High Silica H-zeolite

A portion of the calcined product of Step A. was formed intosilica-bound extrudates of 2 mm as follows:

Components Used Quantity for Preparation (Grams) Silica Sol (Nyacol 1034A) 128.65 Silica gel (aerosil 300) 12.25 H₂PtCl₆ · 6H₂O 2.40 Water(conductivity less than 5 μS/cm) 30.04 Rinse Water 8.00 H-GallosilicateMFI 130.00 Extrusion Aid 0.91 (hydroxypropyl methyl cellulose)

The components were mixed in a food mixer in the order shown. Afteradding the extrusion aid and mixing for about 7 minutes, a smooth pastewas obtained. The paste was extruded into 2 mm extrudates and dried atambient temperature for 3 hours. The air dried extrudates were dried inan oven at 120° C. for 16 hours. After drying, the strands were brokenin 5 mm pieces. The total weight of the dried extrudate was 144.3 grams.The dried extrudates were then calcined in air at 490° C. for 8 hours.

C. Conversion to Zeolite-bound MFI Gallosilicate High Silica Zeolite

The silica-bound extrudates were converted into zeolite-bound highsilica zeolite as follows:

Components Used Quantity for Preparation (Grams) Solution A NaOH pellets(98.6%) 1.438 Gallia (99.995%) 0.177 Water (conductivity less than 5μS/cm) 20.45 Rinse Water 30.14 Solution B Tetrapropylammonium bromide(99%) 9.95 Water (conductivity less than 5 μS/cm) 20.20 Rinse Water30.23

Solutions A and B were poured into a 300 ml stainless steel autoclaveand mixed. Next, 75.0 grams of the silica-bound high silica zeoliteextrudates of Step B were added to the contents of the autoclave. Themolar composition of the synthesis mixture was:

0.47Na₂O/0.025Ga₂O₃/10SiO₂/150H₂O

The autoclave was placed into an oven. The oven was heated from roomtemperature to 150° C. in 2 hours and maintained at this temperature for80 hours. The resulting product was washed to a conductivity of 50 μS/cmwith hot water. The extrudates were dried at 120° C. The weight of thedry product was 78.85 grams. The product was then calcined in air at490° C. for 16 hours.

The product was analyzed by XRD and SEM with the following results:

XRD: Excellent crystallinity

SEM: Core crystals coated and glued together by a myriad of nano-sizedand submicron sized crystals

Elemental:

Core crystals: SiO₂/Ga₂O₃=190

Binder crystals: SiO₂/Ga₂O₃=400

Platinum=0.5 wt. %

EXAMPLE 2

The procedures of steps A and B of Example 1 were repeated to prepare asilica-bound high silica zeolite except aluminosilicate MFI structuretype high silica zeolite was prepared following the procedure of Step Aand the silica-bound high silica zeolite extrudates were formed usingthis material and following the procedure of Step B. The resultingsilica-bound high silica zeolite extrudates were converted tozeolite-bound high silica zeolite. A synthesis mixture with a molarcomposition of 0.48Na₂/O/1.01TPABr/10SiO₂/148H₂O was prepared using thesame procedure as described in Step C of Example 1. In the composition,the silica is present in the extrudates. The mixture was crystallized at150° C. during 80 hours. The resulting zeolite-bound high silica zeolitewere washed, dried and calcined following the procedure described inStep C. SEM showed that the product was comprised of aluminosilicate MFIstructure type high silica zeolite crystals which were coated and gluedtogether by submicron sized silicalite crystals.

EXAMPLE 3

To show the importance of extruding an extrusion paste containing highsilica H-zeolites rather than zeolites in the alkali form, e.g., sodiumform, an extrusion paste was prepared following the same procedures ofSteps A and B of Example 1 except that MFI gallosilicate high silicazeolite in the sodium form was used in place of MFI gallosilicate highsilica H-zeolite in the mixture that formed the extrusion paste. Thepaste was not smooth, lacked plasticity, and was not extrudable.

We claim:
 1. A process for converting hydrocarbons comprising contactinga hydrocarbon feedstream under hydrocarbon conversion conditions with azeolite-bound high silica zeolite which does not contain significantamounts of non-zeolitic binder and comprises high silica zeolitecrystals and zeolite binder crystals said zeolite-bound high silicazeolite prepared by a process which comprises: (a) providing a mixtureof high silica zeolite in the hydrogen form, water, and silica toprovide an extrudable mass; (b) extruding said extrudable mass to form asilica-bound high silica zeolite extrudate; and (c) converting thesilica of the binder of said extrudate to a zeolite binder.
 2. Theprocess recited in claim 1, wherein the silica binder is converted tosaid zeolite binder by aging at an elevated temperature saidsilica-bound high silica zeolite aggregate in an aqueous ionic solutionwhich contains hydroxy ions such that the initial molar ratio of(OH⁻):(SiO₂) is in the range of from about 0.05 to about 1.2.
 3. Theprocess recited in claim 2, wherein said high silica zeolite has a largepore or an intermediate pore size.
 4. The process recited in claim 3,wherein said zeolite binder crystals are intergrown and form at least apartial coating on said high silica zeolite crystals.
 5. The processrecited in claim 3, wherein said zeolite binder crystals have an averageparticle size that is less than said high silica zeolite crystals. 6.The process recited in claim 5, wherein said high silica zeolitecrystals have an average particle size greater than about 0.1 micron. 7.The process recited in claim 6, wherein said hydrocarbon conversion isselected from the group consisting of cracking of hydrocarbons,isomerization of alkyl aromatics, disproportionation of toluene,transalkylation of aromatics, alkylation of aromatics, reforming ofnaphtha to aromatics, conversion of paraffins and/or olefins toaromatics, conversion of oxygenates to hydrocarbon products, cracking ofnaphtha to light olefins, and dewaxing of hydrocarbons.
 8. The processof claim 7, wherein said hydrocarbon conversion is carried out atconditions comprising a temperature of from 100° C. to about 760° C., apressure of 0.1 atmosphere to 100 atmospheres, a weight hourly spacevelocity of from about 0.08 hr⁻¹ to about 200 hr⁻¹.
 9. The processrecited in claim 8, wherein said high silica zeolite has a structuretype selected from the group consisting of *BEA MFI, MEL, MEI, MTW, MTT,TON, and mixtures thereof.
 10. The process recited in claim 9, whereinthe composition of said high silica zeolite has the following molarrelationship: X₂O_(3:):(n)YO₂, wherein X is aluminum, iron, boron,gallium or mixtures thereof and Y is as silicon, tin, germanium ormixture thereof and n has a value greater than
 80. 11. The processrecited in claim 9, where at least 90 percent of the exchangeable alkaliions of said high silica zeolite have been replaced by hydrogen ions.12. The process recited in claim 3, wherein said extrudable mass isextruded using a ram extruder.
 13. The process recited in claim 3,wherein said extrudable mass is extruded using a screw extruder.
 14. Theprocess recited in claim 9, wherein said binder zeolite has a silica toalumina mole ratio greater than about 200:1 or a silica to gallia moleratio greater than about 100:1.
 15. The process recited in claim 14,wherein said high silica zeolite has a silica to alumina mole/ratio offrom greater than 80:1 to about 700:1 or a silica to gallia mole ratiofrom greater than 80:1 to about 500:1.
 16. The process recited in claim10, wherein n has a value greater than
 100. 17. The process recited inclaim 9, wherein the zeolite binder has a structure type that isdifferent from the structure type of said high silica zeolite.
 18. Theprocess recited in claim 9, wherein the zeolite binder has the samestructure type as said high silica zeolite.
 19. The process recited inclaim 9, wherein the binder zeolite has lower acidity than the zeolitein the extrudate.
 20. The process recited in claim 9, wherein the binderzeolite has higher acidity than said high silica zeolite.
 21. Theprocess recited in claim 3, wherein said high silica zeolite and saidbinder zeolite have a MFI or MEL structure.
 22. The process recited inclaim 3, wherein the hydrogen form of said high silica zeolite isprepared by ion exchanging ammonium ions for alkali ions present in saidhigh silica zeolite and decomposing said exchanged ammonium ions. 23.The process recited in claim 21, wherein said zeolite-bound high silicazeolite contains less than 5 percent by weight of non-zeolite material.24. The process recited in claim 21, wherein said hydrocarbon conversionis toluene disproportionation.
 25. The process recited in claim 24,wherein said catalyst is selectivated.
 26. The process recited in claim21, wherein said hydrocarbon conversion is xylene isomerization.
 27. Theprocess recited in claim 26, wherein said hydrocarbon conversion furthercomprises ethylbenzene conversion and said catalyst further comprises atleast one Group VIII metal.